The present invention relates to a segmented stator end turn air deflector for a force ventilated AC motor and, more particularly, to a method and apparatus for directing the air flow of dynamo electric machines such as an AC electric motor or an alternator through the stator end turns for more efficient cooling.
Typical dynamo electric machines such as AC electric motors or alternators are formed of a rotatable rotor and a fixed stator. Stators are normally formed of a series of thin, flat plates stacked to form a solid body. Coils or windings are positioned in pre-formed slots in the plates, extending through the stack, with ends of the coils looping at each end of the stack to form end turns. The stator is normally cooled by air blowing through passages in the stator. Some air flows through the gap between the stator and the rotor. All of the air exits the machine through openings in an end of the housing (the "end bell") supporting the stator. As the air exits in a longitudinal direction, very little of the air actually passes through the coil end turns.
In general, prior art methods and apparatuses for increasing the efficiency of force ventilated AC motors by more efficient cooling have been directed to methods suitable only for initial manufacturing. For example, U.S. Pat. No. 5,214,324 to Holmes describes a stator air baffle provided to redirect cooling air flow exiting the stator of an electric motor. The air baffle is provided at the air outlet end of the motor and extends between the stator frame and the stator coils so that air is redirected to pass through the coil end turns before exiting the motor. The baffle is fixed to the coils but is loosely mounted to the stator frame in a floating manner so that the entire assembly is free to rotate and can have limited longitudinal motion when necessary according to the operating condition of the motor.
U.S. Pat. No. 5,306,972 to Hokanson et al. describes an AC motor system having a rotor and a stator with the rotor having a plurality of air passages for passing cooling air and the stator having winding end turns extending from each end. An air deflector is coupled to one end of the rotor and has a generally curved configuration for directing cooling air exiting the air passages into a generally radial flow direction and onto the stator end windings. The stator end windings comprise turns of a plurality of electrical conductors forming the stator windings circuits which are wound to form a plurality of phase windings. Accordingly, the prior art has not disclosed a retrofittable baffle assembly which can be used to improve the efficiency of force ventilated AC motors.